Device and method for controlling power in mobile terminal

ABSTRACT

A device and a method for controlling a transmission power in a mobile terminal are provided. The device includes an antenna set in an optimized state, a memory including a power control table that includes transmission power control data for satisfying a Specific Absorption Rate (SAR) standard in a state where efficiency of the antenna is optimized, a sensor for detecting a distance between the mobile terminal and a user, a controller for receiving distance data from the sensor and for outputting transmission power control data corresponding to the distance data by referring to the power control table, and a power amplifier connected between a transmitter and the antenna for controlling transmission power of a signal according to the transmission power control data and for outputting the signal to the antenna.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 14/310,588, filed on Jun. 20, 2014, which is a continuationapplication of prior application Ser. No. 13/246,238, filed on Sep. 27,2011, which has issued as U.S. Pat. No. 8,798,664 on Aug. 5, 2014 andclaimed the benefit under 35 U.S.C. §119(a) of a Korean patentapplication filed on Sep. 28, 2010 in the Korean Intellectual PropertyOffice and assigned Serial number 10-2010-0093769, the entire disclosureof which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device and a method for controllingtransmission power in a mobile terminal. More particularly, the presentinvention relates to a device and a method for satisfying a SpecificAbsorption Rate (SAR) standard by controlling transmission powerdepending on a distance between a mobile terminal and a user.

2. Description of the Related Art

Generally, a mobile terminal is used in such a manner that the mobileterminal is disposed adjacent to a user's head between the user's earand mouth. In this case, the electromagnetic wave generated in themobile terminal during a call may affect the health of the user.Therefore, every country designs a Specific Absorption Rate (SAR)standard to define the permissible amount of electromagnetic energy themobile terminal may generate. The SAR standard for the bands of eachregion is different. For example, in a case of European bands (e.g.,GSM900, DCS, W900, W2100), the SAR standard is 2.0 W/kg (10 g average).Whereas, in a case of Central and South American bands (e.g., GSM850,PCS, W850, W1900), the SAR standard is 1.6 W/KG (1 g average), which isa more stringent SAR standard. A method for controlling the performanceof an antenna is used in the related art to satisfy the SAR standard. Inthis case, the performance of the antenna is unable to be optimized sothat the SAR International standard may be satisfied (i.e., avoid afailure or margin shortfall) even when the performance of the antenna infree space can be sufficiently enhanced. For example, in a case wherethe mobile terminal is being brought to a global market, it might benecessary to lower the performance of the antenna of the mobile terminalso as to satisfy (i.e., avoid a failure or margin shortfall) the SARstandard in the Central and South American bands where the SAR standardis more stringent than the European bands. This is more likely the casewhen a mobile terminal for Central and South America is developed aftercompleting the development of the optimized performance of the antennafor Europe. Hence, in the mobile terminal of the related art, theperformance of the antenna cannot be optimized so that the SARInternational standard is satisfied, even when the performance of theantenna in free space can be sufficiently enhanced. Accordingly, theperformance of an antenna is lowered to the free space transmission andreception rate. In order to address such a problem, when antennascorresponding to respective mobile terminals (i.e., a mobile terminalfor Europe and a mobile terminal for Central and South America) using adifferent SAR standard are used, there is a delay in the development ofan antenna and an increase in costs such as a maintenance cost and aninventory cost.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a device for reducing Total Radiated Power (TRP)of an antenna of a total or specific band at a close proximity of amobile terminal while achieving a high performance of the antenna infree space, and a method thereof.

Another aspect of the present invention is to measure a distance betweena user and a mobile terminal using a sensor (e.g., a proximity sensor),and control transmission power according to the measured result tomaximize the antenna performance while satisfying human head SAR.

In accordance with an aspect of the present invention, a device forcontrolling transmission power in a mobile terminal is provided. Thedevice includes an antenna set in an optimized state, a memory includinga power control table that includes transmission power control data forsatisfying a Specific Absorption Rate (SAR) standard in a state whereefficiency of the antenna is optimized, a sensor for detecting adistance between the mobile terminal and a user, a controller forreceiving distance data from the sensor and for outputting transmissionpower control data corresponding to the distance data by referring tothe power control table, and a power amplifier connected between atransmitter and the antenna for controlling transmission power of asignal according to the transmission power control data and foroutputting the signal to the antenna.

In accordance with another aspect of the present invention, a method forcontrolling transmission power in a mobile terminal is provided. Themethod includes detecting a distance between the mobile terminal and auser in a call mode, wherein the mobile terminal includes a powercontrol table that includes transmission power control data forsatisfying a Specific Absorption Rate (SAR) standard in a state whereefficiency of an antenna is optimized, acquiring transmission powercontrol data corresponding to the detected distance from the powercontrol table, when the detected distance is less than a presetdistance, and controlling transmission power of a signal according tothe transmission power control data.

In accordance with another aspect of the present invention, a device forcontrolling transmission power in a mobile terminal is provided. Thedevice includes an antenna set in an optimized state, a memory includinga plurality of power control tables according to a SAR standard of acountry or zone, the plurality of power control tables includingtransmission power control data for satisfying a Specific AbsorptionRate (SAR) standard in a state where efficiency of the antenna isoptimized, a sensor for detecting a distance between the mobile terminaland a user, a controller for selecting a power control table of acountry or zone in which the mobile terminal is located, for receivingthe detected distance data from the sensor in a call mode, and foroutputting transmission power control data corresponding to the detecteddistance by referring to the power control table, and a power amplifierconnected between a transmitter and the antenna for controllingtransmission power of a signal according to the transmission powercontrol data and for outputting the signal to the antenna.

In accordance with another aspect of the present invention, a method forcontrolling transmission power in a mobile terminal is provided. Themethod includes setting a power control table of a country or zone inwhich the mobile terminal is located, wherein the mobile terminalincludes a memory that includes a plurality of power tables according toa Specific Absorption Rate (SAR) standard of a country or zone, thepower table including transmission power control data for satisfying aSAR standard in a state where efficiency of an antenna is optimized,detecting a distance between the mobile terminal and a user in a callmode, acquiring transmission power control data corresponding to thedetected distance from the power control table, when the detecteddistance is less than a preset distance, and controlling transmissionpower of a signal according to the transmission power control data.

Therefore, a mobile terminal according to exemplary embodiments of thepresent invention may maximize the performance of an antenna in freespace. The same material is applicable to antennas of mobile terminals(e.g., mobile terminals for Europe and America/Central and SouthAmerica) having different SAR standards to reduce a development time andcost of a mobile terminal.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a block diagram illustrating a configuration of a mobileterminal according to an exemplary embodiment of the present invention;and

FIG. 2 is a flowchart illustrating a method for controlling SpecificAbsorption Rate (SAR) of a mobile terminal according to an exemplaryembodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

A mobile terminal according to an exemplary embodiment of the presentinvention optimizes the performance of an antenna, measures a distancebetween the mobile terminal and a user using a sensor (e.g., a proximitysensor), and controls power of a transmission signal to satisfy aSpecific Absorption Rate (SAR) standard. Accordingly, a mobile terminalaccording to an exemplary embodiment of the present invention maycontrol Total Radiated Power (TRP) of an antenna according to a distancebetween a user and the mobile terminal while achieving a highperformance of the antenna, thereby dynamically satisfying the SARstandard.

FIG. 1 is a block diagram illustrating a configuration of a mobileterminal according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the mobile terminal includes a controller 100, amemory 110, a sensor 120, a transmitter 130, a power amplifier 140, aduplexer 150, a receiver 160, and an antenna 170. The duplexer 150transfers a signal received through the antenna 170 to a receiver 160,and performs transmission/reception of a Radio Frequency (RF) signalthrough the antenna 170 based on a signal output from a power amplifier140. The receiver 160 RF-converts and frequency-down-converts a signalreceived through the duplexer 160 into a baseband signal. Further, thereceiver 160 may include a demodulator and a decoder. In this case, thereceiver 160 demodulates and decodes the baseband signal.

The sensor 120 detects a distance between the mobile terminal and auser. The sensor 120 may be a proximity sensor. The proximity sensor isused to determine whether an object approaches another object beforecontacting it. The proximity sensor may be classified into highfrequency transmittance type, a capacitive type, a magnetic type, aphotoelectric type, and an ultrasound type. Here, the sensor 120 may usean optical proximity sensor or an ultrasound proximity sensor. In thiscase, when the sensor 120 is the optical proximity sensor, the sensor120 includes a light emitting unit and a light receiving unit.

Further, the sensor 120 may include a sensing unit for measuring adistance between the mobile terminal and a user. At this time, thesensing unit may be configured as one of two types. A first type ofsensing unit detects whether the light receiving unit receives a lightsource emitted from the sensor 120. In this case, the sensing unit maybe an optical sensing unit or a distance sensing unit. When the lightreceiving unit receives a light source emitted from the light emittingunit of the sensor 120, the optical sensing unit generates a detectingsignal indicating that the mobile terminal approaches the user. When thelight receiving unit does not receive the light source emitted from thelight emitting unit of the sensor 120, the optical sensing unitgenerates a detecting signal indicating that the mobile terminal isspaced apart from the user. At this time, the optical sensing unit maymeasure an amount and intensity of received light to calculate adistance between a user and a mobile terminal When the light receivingunit receives the light source emitted from the light emitting unit, thesecond type of sensing unit further calculates a difference between alight emitting time and a light receiving time to calculate a distancebetween the user and the mobile terminal. When the light receiving unitdoes not receive the light source, the sensing unit detecting thedistance does not generate a detecting signal. When the light receivingunit receives the light source, the sensing unit calculates a distancebetween a light emitting signal and a light receiving signal and adetecting signal to output a distance data between the mobile terminaland the user. Although it is assumed in an exemplary embodiment of thepresent invention that the sensing unit has a distance sensing function,the same results may be obtained with the first type sensing unit.

The memory 10 includes a program memory for storing programs thatcontrol operations of the mobile terminal, and a data memory for storingdata used when executing programs and data created during the executionof the programs. The data includes a power control table for controllingtransmission power according to a distance between the mobile terminaland the user while satisfying the SAR standard for the frequency bandaccording to an exemplary embodiment of the present invention.

The controller 100 performs a function of controlling overall operationsof the mobile terminal. Further, when the sensor 120 does not include asensing unit, the controller 100 may further include the sensing unit.When the receiver 160 and a transmitter 130 do not have modem and codecfunctions, the controller 100 may include the modem and codec functionsand may further include a data processor for modulating/demodulating andencoding/decoding transmission and reception data. The controller 100analyzes a detecting signal received from the sensor 120. When adistance between the user and the mobile terminal is less than a presetdistance, the controller 100 generates a power control signal forcontrolling transmission power.

The transmitter 130 frequency-up-converts a transmission signalgenerated by a sender (not shown) or a peripheral interface. Here, thetransmitter 130 may include an encoder for encoding a signal and amodulator for modulating an encoded signal.

The power amplifier controls power of a signal output from thetransmitter 130 and transfers the amplified signal to the duplexer 150.At this time, the power amplifier 140 controls power of a transmissionsignal output from the transmitter 130 according to a power controlsignal output from the controller 100. Here, the power amplifier may bea linear power amplifier.

The power control table stored in the memory 110 is configured by datafor controlling transmission power to satisfy a SAR standard in anoptimized state (namely, a set state of maximum antenna efficiency) ofantenna gain. Here, assuming that maximum transmission power is 33 dBm,an antenna optimization value is dBi, and SAR is 1.6 W/kg, transmissionpower is changed according to a distance detected while having a highperformance of the antenna to satisfy the SAR standard. In this case,since transmission power is only controlled according to a distancebetween the mobile terminal and the user, reception efficiency of areceiving side may be improved while satisfying the SAR standard. Atthis time, the SAR standard may change according to countries or zones(e.g., Central and South America, Europe, etc.). Accordingly, the powercontrol table stored in the memory 110 may be a power control tableconfigured corresponding to a country or a zone in which the mobileterminal is used. Further, if the mobile terminal can process signals ofplural bands using different SAR standards, it may include power controltables of the corresponding SAR standards.

First, the controller 100 determines a type (e.g., WCDMA850, WCDMA 1900,etc.) of terminal upon initialization of a system, determines the SARstandard according to the determined type of terminal, and determines apower control table according to the determined SAR standard. Here, thepower control table is stored in the memory 110. The power control tableis a look-up table storing information for controlling transmissionpower of a terminal according to a distance between the mobile terminaland a user. The power control table may include distance data andtransmission power control data corresponding thereto.

In the foregoing state, the controller 100 determines a distance betweenthe mobile terminal and the user based on the output of the sensor 120.Next, the controller 100 determines transmission power control datacorresponding to the determined distance from the power control table ofthe memory 110 and then outputs the transmission power control data tothe power amplifier 140. In this case, the power amplifier 140 controlstransmission power of a signal output from the transmitter 130 accordingto the transmission power control data, and outputs the signal throughthe antenna 170.

Accordingly, the mobile terminal uses the sensor 120 to determinewhether the user brings the mobile terminal toward the ear when themobile terminal is in a call state. If the user brings the mobileterminal toward the ear and the mobile terminal is in a call state, themobile terminal determines the distance there between so as to controlthe transmission power of a signal. The transmission power control dataoutput from the controller 100 may be a signal controlling output of thepower amplifier to an amplitude capable of satisfying the SAR standardaccording to the determined distance. Accordingly, upon manufacturingthe mobile terminal, the SAR standard may be satisfied without changingthe performance of the antenna. At this time, since the receiver 160receives a signal in a state where the antenna has a high performance,although transmission power changes, reception power maintains as it is.Thus, constant reception efficiency may be retained regardless of a usemethod of the mobile terminal by the user.

FIG. 2 is a flowchart illustrating a method for controlling power of amobile terminal according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, a controller 100 receives the output of the sensor120 in step 211. In this case, the sensor 120 may be a proximity sensor.Further, the controller 100 calculates a distance between the mobileterminal and a user based on the output of the sensor 120. A sensingunit for determining the distance may be included in the sensor 120. Thesensing unit may be provided between the sensor 120 and the controller100, or inside the controller 100. Next, the controller 100 determineswhether the determined distance is less than a preset distance byreferring to the power control table of a memory 110 in step 213. Here,the preset distance may refer to a reference distance capable oftransmitting a signal with a maximum transmission power of a poweramplifier 140 without controlling transmission power in a statesatisfying a SAR standard. If it is determined that the determineddistance between the mobile terminal and the user exceeds the presetdistance (that is, the mobile terminal is sufficiently spaced apart fromthe user), the controller 100 outputs transmission power control data tothe power amplifier 140 such that the power amplifier 140 can amplifypower of a signal to a maximum transmission power in step 219.Accordingly, the transmission signal output from the transmitter 130 isamplified to maximum transmission power by the power amplifier 140 andthe amplified signal is output through the duplexer 150. The signalreceived through the duplexer 150 is processed by the receiver 160.

Conversely, when the detected distance (i.e., the distance between themobile terminal and the user) is less than the preset distance at step213, the controller 100 acquires the transmission power control datacorresponding to the detected distance with reference to the powercontrol table of the memory 110 in step 215, and outputs thetransmission power control data to the power amplifier 140 in step 217.At this time, the transmission power control data is used to reduce thetransmission power to satisfy the SAR standard in a state where theperformance of the antenna is optimized. The power control may occurwhen the mobile terminal contacts or is proximate to an ear of a user.In this case, the controller 100 performs a control operation forreducing the transmission power to satisfy the SAR standard. At thistime, the controller 100 satisfies the SAR standard while reducing thetransmission power while a received signal is not influenced. When themobile terminal includes a plurality of power control tables forsatisfying a plurality of SAR standards, that is, when the mobileterminal is a mobile terminal usable in a plurality of countries orzones having different SAR standards, the mobile terminal may furtherincludes an operation procedure for determining a country or a zonewhere a current mobile terminal is located upon powering on, and settinga power control table corresponding to the determined country or zone.That is, when the mobile terminal is a mobile terminal including an RFcommunication unit having two or more bands with different SARstandards, the mobile terminal further includes respective power controltables corresponding to the plurality of SAR standards. In a bootingprocedure of the mobile terminal, a power control table is setcorresponding to the SAR standard of a country or zone in which themobile terminal is located, and transmission power is controlled usingthe set power control table in a call mode.

As illustrated above, exemplary embodiments of the present inventioncontrol transmission power according to a state in which the mobileterminal approaches the user and when the performance of antenna isoptimized, thereby efficiently controlling transmission and receptionoperation while satisfying a SAR standard.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method comprising: detecting, via a sensor ofan electronic device, a distance between a user and the electronicdevice adapted to transmit a signal using a transmission power;adjusting, using a processor of the electronic device, the transmissionpower based at least in part on a determination that the distance fallsinto a specified range; and transmitting, via an antenna of theelectronic device, the signal using the adjusted transmission power. 2.The method of claim 1, wherein the sensor comprises a proximity sensor.3. The method of claim 1, wherein the adjusting of the transmissionpower comprises: acquiring power control data corresponding to thedistance from a power control table stored at the electronic device,;and determining power strength for the adjusted transmission poweraccording to the power control data.
 4. The method of claim 3, whereinthe acquiring of the power control data comprises: selecting the powercontrol table from a plurality of power control tables based at least inpart on a location of the electronic device.
 5. The method of claim 3,wherein the power control table comprises a first power control tableand a second power control table, the first power control tableincluding first transmission power control data corresponding to a firstcountry or a first area, and the second power control table includingsecond transmission power control data corresponding to a second countryor a second area.
 6. The method of claim 1, wherein the adjusting of thetransmission power comprises: decreasing or increasing the transmissionpower as the distance is decreased or increased, respectively.
 7. Themethod of claim 1, wherein the adjusting of the transmission powercomprises: setting, as the adjusted transmission power, a power thatsatisfies a specific absorption rate (SAR) standard of a country or areain which the electronic device is located.
 8. The method of claim 1,wherein the transmitting of the signal comprises: transmitting thesignal using the transmission power as unadjusted if the distance doesnot fall into the specified range.
 9. The method of claim 1, wherein thedetecting of the distance between the user and the electronic devicecomprises: detecting the distance while the electronic device is in acall mode.
 10. An apparatus comprising: an antenna configured totransmit a signal using a transmission power; a sensor configured todetect a distance between a user and the apparatus; and a controlleroperatively coupled with the antenna, the controller configured to:adjust the transmission power based at least in part on a determinationthat the distance falls into a specified range, and transmit, via theantenna, the signal using the adjusted transmission power.
 11. Theapparatus of claim 10, wherein the controller is further configured to:receive, via the antenna, a reception signal using a reception powerdifferent from the transmission power.
 12. The apparatus of claim 11,wherein the controller is further configured to: maintain a receptionefficiency during the receiving of the reception signal.
 13. Theapparatus of claim 10, further comprising: a memory configured to storea power control table, wherein the controller is configured to: acquirepower control data corresponding to the distance from the power controltable, and determine power strength for the adjusted transmission poweraccording to the power control data.
 14. The apparatus of claim 10,wherein the controller is further configured to: select the powercontrol table from a plurality of power control tables based at least inpart on a location of the apparatus.
 15. The apparatus of claim 14,wherein the power control table comprises a first power control tableand a second power control table, the first power control tableincluding first transmission power control data corresponding to a firstcountry or a first area, and the second power control table includingsecond transmission power control data corresponding to a second countryor a second area.
 16. The apparatus of claim 10, wherein the controlleris further configured to: decrease or increase the transmission power asthe distance is decreased or increased, respectively.
 17. The apparatusof claim 10, wherein the controller is further configured to: set, asthe adjusted transmission power, a power that satisfies a specificabsorption rate (SAR) standard of a country or area in which theapparatus is located.
 18. The apparatus of claim 10, further comprising:an amplifier, wherein the controller is further configured to controlthe amplifier to amplify the signal using the adjusted transmissionpower.
 19. The apparatus of claim 18, wherein the controller is furtherconfigured to: transmit, via the antenna, the signal using thetransmission power as unadjusted if the distance does not fall into thespecified range.
 20. A machine-readable storage device storinginstructions, the instructions executed by at least one processor causethe at least one processors to perform operations comprising: detecting,via a sensor of an electronic device, a distance between a user and theelectronic device adapted to transmit a signal using a transmissionpower; adjusting, using a processor of the electronic device, thetransmission power based at least in part on a determination that thedistance falls into a specified range; and transmitting, via an antennaof the electronic device, the signal using the adjusted transmissionpower.